This is a Haltec H-5265 standard bore lock on air chuck. This is a specially designed air chuck that locks onto the cap threads of a Standard Bore valve stem when the sliding sleeve is pushed to the forward position. The chuck releases when the sleeve is pulled back. This air chuck connects with a 1/4″” NPT thread size. Haltec is a leading manufacturer of inflation systems and maintains its leadership position as a major manufacturer of specialized tire valve systems.